This invention relates to a method and apparatus for purifying the contamination of a dental consultation room.
Laughing gas, or rather nitrous oxide, has been used recently as an inhaled stupefacient in dental treatment, and a laughing gas sedation process has been employed especially from around 1970. The laughing gas sedation process is a process for reducing the mental and physical distress and pain of the patient during dental treatment by causing the patient to inhale a low concentration of laughing gas so that the treatment can be carried out in cooperation with the patient who is in a related state. When the patient inhales a 20 to 30% concentration of laughing gas, he does not lose consciousness but feels only slight pain and has no anxiety and hence tooth extraction can be made easier than before.
Though laughing gas is believed to have low toxicity and less side effects in comparison with other anesthetics, various problems have occured as the laughing gas sedation process has become widespread. It has been reported that since persons working in dental consultation rooms, such as the dentist, inhale laughing gas, even if its concentration is low, for an extended period of time, the occurrence of disorders such as natural abortion, renal diseases, cancer, antenatal deformities and the like in female workers in the dental consulation room is 1.3 to 2 times that of those who do not inhale anesthetic gases such as laughing gas and the occurrence of heptal diseases in male workers is 1.3 to 2.2 times that of male pediatricians ("Dental Review", Vol. 57, No. 7, June, 1981, "On Laughing Gas Contamination in Dental Range and Health of Dental Workers").
The drilling of the teeth or false teeth of the patient is effected in the dental consulation room by the use of an air turbine engine or an electric engine so that a large quantity of dust occurs. Dust having a particle size of 1.mu. to 5.mu. makes up 80% of the scattered dust and dust having a particle size of 6.mu. to 10.mu. accounts for 20% when an air turbine engine is used, though these values change according to the cutters used. Anyway, the dust is inhaled by the workers inside the dental consulation room. Incidentally, dust having a particle size of 10.mu. or more is caught in the throat and is discharged outside the body together with phelgm and causes no particular problems.
It has been the customary practise that the assistant to the dentist inserts a suction nozzle consisting of a thin elongated pipe into the oral cavity of the patient together with the cutter so as to vacuum suck the dust. It has been found, however, that the dust removing effect of this system is amazingly low and that dust of only up to about 5.mu. can be sucked, and dust having a particle size of up to 5.mu. is scattered around inside the consultation room. Presumably this results from the fact that vortex flows occur inside the oral cavity. Since dust ranging from 0.6.mu. to 5.mu., which is most dangerous to the workers in the dental consultation room such as the dentists, scatter in the consultation room and since bacteria are attached to the dust, the workers are highly likely to be infected with type B hepatitis virus, resulting eventually in the occurrence of hepatic induration and liver cancer. In addition, the saliva and blood of the patient scatter and contaminate the dental consultation room. (Refer to the gazette of the Japan Dental Meterial and Instrument Society, "Contamination of Consultation Room and Counter-Measures", No. 11, September, 1964 and the gazette of the Japan Oral Cavity Surgery Society, "Examination of Type B Hepatitis Virus Infection in Hokkaido", Vol. 26, No. 2, 1980.)
Though the contamination of the dental consultation room by laughing gas and dust has been examined in the past as described above, sufficient counter-measures have not yet been established, especially against laughing gas. As to the latter, a small dust collector called Spotmatic (tradename) has sometimes been installed inside the consultation room but it can not discharge anesthetic gas from inside the consultation room to the outside.